Polymethylbenzyl esters of watersoluble acids



Patented May 29, 1951 POLYMETHYLBENZYL ESTERS OF WATER- SOLUBLE ACIDS Alfred P. Kozacik and Alexander N. Sachanen, Woodbury, N. 3., assignors to Socony-Vacuum Oil Company, Incorporated, a corporation of New York No Drawing. Application June 3, 1948,

Serial No. 30,985

12 Claims.

This invention relates, broadly, to polymethylbenzyl esters of acids derived from the oxidation of hydrocarbons, and is more particularly concerned with the polymethylbenzyl esters of certain acids derived from the oxidation of hydrocarbons.

As is well known to those familiar with the art, certain partially-oxidized hydrocarbon fractions and esters of high molecular weight acids derived from the oxidation of heavy waxes have been proposed as plasticizers, high-boiling solvents, and the like. These products, however, have been limited, in the main, to the.complex and water-insoluble acids derived from the oxidation of hydrocarbons. Heretofore, esters of the water-soluble acids derived by the oxidation of hydrocarbons have been inapplicable for the aforementioned purposes, since these esters have had relatively low-boiling points and, consequently, relatively high vapor pressures.

It has now been found that high-boiling esters of water-soluble acids derived by the oxidation of hydrocarbons can be prepared by a process which is simple and inexpensive.

It has now been discovered that the polymethylbenzyl esters of water-soluble acids derived by the oxidation of hydrocarbons provide high-boiling materials eminently suited for use as plasticizers, high-boiling solvents, and the like.

Accordingly, it is a broad object of the present invention to provide esters of water-soluble acids derived by the oxidation of hydrocarbons by a process which is simple and inexpensive. Another object is to provide high-boiling esters of water-soluble acids, derived by the oxidation of hydrocarbons. An important object is to provide a process for treating acids derived by oxidation of hydrocarbons, to obtain high-boiling esters which are useful as plasticizers and highboiling solvents. Other objects and advantages of the present invention will become apparent to those skilled in the art from the following description.

Broadly stated, the present invention provides polymethylbenzyl esters of water-soluble acids derived by the oxidation of hydrocarbons obtained by a process which comprises oxidizing hydrocarbons, treating the oxidized product with caustic material to sapcnify and neutralize the saponifiable and neutralizable matter present in the oxidized product, separating the saponifiable and neutralizable matter from the thus-treated oxidized product, treating the saponifiable and neutralizable matter with acidic material, sepa-- rating the water-soluble saponifiable and neutralizable matter, treating said Water-soluble saponifiable and neutralizable matter with a basic alkali-metal compound to form an alkalimetal salt of said water-soluble saponifiable and neutralizable matter, reacting the alkali-metal salt with a halogen-substituted polymethylbenzyl to form a reaction product, extracting the reaction product with a non-polar solvent, and topping the extract thus obtained to obtain the polymethylbenzyl esters of the water-soluble saponiiiable and neutralizable matter.

Any hydrocarbon mixture containing upwards of about per cent by volume of aliphatic and naphthenic hydrocarbons may be oxidized to provide the acids utilizable in this invention. In practice, the source of hydrocarbons is a petroleum hydrocarbon fraction boiling above about 300 F. and, preferably, a fraction which has a boiling range varying between about 400 F. and about 700 F.

Any method for eiTecting the oxidation of hydrocarbons may be used to prepare the oxidized hydrocarbons utilized in the process of this in vention. The procedures disclosed in the patents to Burwell, U. S. Patents Nos. 1,690,768 and 1,690,769,, are typical of the operations involved. ihe source of oxygen may be air, oxygen, or inorganic chemicals which readily give up oxygen, such as certain dichromates, peroxides, etc. It is immaterial, for the purposes of this invention, whether the oxidation is carried out by a catalytic or a non-catalytic process. Likewise, the temperature and the pressure involved are not pertinent factors. vention is predicated in part on the discovery that regardless of the oxidation process utilized, the water-soluble acids obtained are suitable for use in preparing the polymethylb'enzyl esters contemplated herein.

In order to saponify substantially all of the saponifiable constituents present in the products of oxidation, 1. e., the esters, lactides, etc., and to neutralize substantially all the organic acids likewise present therein, in accordance with the present invention, the end-products of the oxidation operation are treated with an aqueous solution of caustic material. In practice, an aqueous solution of an alkali-metal hydroxide, such as sodium or potassium hydroxide, is preferred. It must be clearly understood, however, that other alkaline materials may be used, such as ammonium hydroxide, sodium carbonate, etc. The temperature and time of saponification and neutralization may be readily ascertained by any one skilled in the art. Thus, for example, it

In fact, the present inwill be apparent that higher temperatures induce a greater degree of saponification and neutralization within a shorter period of time. For all practical purposes, the reflux temperature of the aqueous reaction mixture is preferred.

Upon cooling the product of the saponification and neutralization operation, the mixture will separate into two strata. The heavier, aqueous stratum will comprise water-soluble metal salts of the organic acids produced during the oxida: tion operation, and the saponification and. mmtralization operation. The supernatant stratum will comprise water-insoluble, unsaponifiable and unneutralizable matter. These strata are. separated from each other by any of the well-known applicable techniques, such as decantation. Then,

preferably, in order to remove residual amounts of water-insoluble, unsaponifiable and unneutralizable matter, the aqueous stratum is washed with solvents which are substantially immiscible with water. Non-limiting examples of suitable solvents are light petroleum ether, diethyl ether, and. benzene. The washing operation is carried out preferably at room temperature (68 F.), although higher or lower temperatures may be suitably employed.

In order to release the organic acids from the water-soluble metal salts thereof, the solventwashed aqueous stratum is treated with an acidic material in amounts sufiicient to neutralize all of the alkaline material present in the aqueous straturn. This acidic material may be a mineral acid, such as hydrochloric acid or sulfuric acid, or it may be an organic acid, such as, for example, acetic acid. As a result of this treatment, there will be produced an oily layer containing waterinsoluble acids and an aqueous layer containing the water-soluble acids. The oily layer is separated from the aqueous layer, as by decantation. Then, the aqueous layer is preferably washed with a solvent which is substantially immiscible with water, such as light petroleum ether, benzene, or diethyl ether, in order to remove any residual amounts of oily organic acids.

In order to obtain an aqueous solution of the water-soluble salts of the water-soluble organic acids, the aqueous solution of the water-soluble acids is neutralized with a caustic material or an aqueous solution of a caustic material, such as sodium or potassium hydroxide, ammonium hydroxide, or sodium carbonate. The aqueous solution of metal salts of the Water-solubleorganic acids, thus obtained, may be used per se in the esterification operation. It is preferable, however, to concentrate the metal salts of the Watersoluble organic acids, such as by evaporation, even substantially to the point of dryness.

In accordance with the present invention, esterification of the water-soluble organic acids is effected by reacting the sodium salts thereof, as obtained hereinbefore with a halogen-substituted polymethylbenzene, such as polymethylbenzyl halide or a halogenated polymethylbenzyl halide. Especially suited for the purposes of the present invention are the polymethylbenzyl chlorides such as, for example, dimethylbenzyl chlorides and trimethylbenzyl chlorides. As is well known to those familiar with the art, highly aromatic petroleum fractions, comprising mixtures of methylbenzenes are obtainable in high yields by cracking, particularly catalytic cracking operations. As is well known to those familiar with the art, direct, non-catalytic chlorination of these fractions, under appropriate reaction conditions,

produces chlorinated derivatives in which only,

the methyl groups are chlorinated, leaving the ring substantially unaifected. By careful control of the reaction conditions, predominantly monochloromethylbenzenes can be produced. By another method, also well known to the art, chloromethyl groups may be introduced in the benzene ring by means of the so-called chloromethylation reaction involving the use of hydrochloric acid and formaldehyde.

Inpractice, the esterification of the water-soluble organic acids is effected by reacting solid metal salts of the water-soluble organic acids with an excess of a halogen-substituted polymethyl benzene over the amount required to re" act with the water-soluble acids, in the presence of a non-polar solvent, such as benzene, toluene, or xylene, which forms an azeotropic mixture with water which may be present in the solid salts in-a smallamount. The amount of solvent used is not critical. The reaction mixture is heated, so as toremove all of the solvent and the water as an azeotropic mixture. Finally, the reaction is completed by heating the reaction mixture at a temperature varying between about 370 F. and about 390 F. for a period of time varying between about ten hours and about twenty hours.

The. resultant reaction, product is extracted with a non-polar hydrocarbon solvent, such as light petroleum ether, benzene, toluene, or xylene, to remove all soluble organic materials. The solvent is removed from the solution thus obtained, as by distillation, and the residue is subjected to distillation at a temperature of about C. under a pressure of about 15 millimeters. The distillate will contain the unreacted organic material and the lastv traces of solvent. The residue will comprise the desired polymethylbenzyl ester product.

The following specific example illustrates the mode of preparing the polymethylbenzyl esters of water-soluble organic acids in accordance with the present invention. It is to be clearly understood, however, that the invention is not to be limited to the specific embodiment set forth hereinafter, or to the operations and manipulations described therein. As will be apparent to those skilled in the .art, a wide variety of other solvents, hydrocarbon mixtures, and halogen-substituted polymethylbenzenes, as set forth hereinbefore, may be used to prepare the esters in accordance with this invention.

Example I Lightwhite oil (acidtreated kerosene) comprising paraidnic and naphthenic hydrocarbons and having a boiling-range of about 450-516 F., a specific gravity of about 0.8076, and an aromatic content of less than about 2% by volume, was oxidized under atmospheric pressure, at a temperature. of 302. F. Oxidation was effected by charging oxygen at the rate of 885 cubic centimeters per minute for about 28 hours. The resulting product had a neutralization number (number of milligramsof KOH equivalent to one gram of substance).of 108.3 and a saponification number of 243.0.

The resulting oxidized light white oil was saponified and neutralized with 1830 cubic centimeters of an aqueous. solution containing 5'78 grams of sodium hydroxide, at a temperature of 212 F. for about four hours. Afterstanding and cooling, the reaction mixture formed two layers, namely, a supernatant layer of unsaponifiable and unneutralizable matter and an alkaline aqueous, layer comprising a solution of the sodium salt of the saponifiable and neutralizable matter. The layer of saponifiable and neutralizable matter was separated and then washed with benzene to remove residual unsaponifiable and unneutrajlizable matter. The alkaline layer was aciditied with an amount of concentrated hydrochloric acid equivalent to the sodium hydroxide used for the saponication operation. The aqueous layer of water-soluble organic acids was separated from the layer of water-insoluble organic acids. The later was washed with distilled water until free of water-soluble acids, and the washes were combined with the main body of the solution of water-soluble acids. This solution was neutralized with an aqueous solution of sodium hydroxide and the resultant solution was evaporated to dryness. The solid thus obtained was pulverized in a roller mill and dried in an oven at a temperature of about 212? F. for about hours. The resultant brown powder had an analysis of 29.5 per cent sodium and 37.8 per cent chlorine.

The powder containing the sodium salts of the water-soluble organic acids (1225 grams), 465 grams of a trimethylbenzylchloride (chlorine content=20.3 per cent) obtained by chloromethylation of a petroleum fraction of high aromatic content (boiling range=300-367 R), and 200 cubic centimeters of benzene were placed in a 5-liter flask equipped with a motor-driven paddle stirrer, thermometer, and a water-trap fitted with a condenser. The reaction mixture was gradually heated, with stirring, and benzene and water were removed from the water-trap. When all the benzene had been removed, the reaction mixture was heated at a temperature of about 392 F. for about 22 hours. The mixture was cooled and the organic-soluble material was extracted therefrom with benzene. The benzene solution containing the polymethylbenzyl esters was filtered, and the benzene was removed by distillation. The remaining material was subjected to distillation at millimeters and a distillate boiling up to 230 F. was collected. The residue contained the desired polymethylbenzyl esters of the water-soluble organic acids. The following data were obtained for the two fractions:

Although the present invention has been described in conjunction with preferred embodiments, it is to be understood that modifications and variations may be resorted to, without departing from the spirit and scope of this invention, as those skilled in the art will readily understand. Such variations and modifications are considered to be within the purview andscope of the appended claims.

We claim:

1. In the process which includes oxidizing a hydrocarbon mixture containing upwards of about 80% by volume of aliphatic and naphthenic hydrocarbons and boiling above about 300 F. to produce an oxidized product, treating the oxidized product with a caustic material to saponiiy and neutralize the saponifiable and neutralizable matter present in said oxidized product, separating the saponifiable and neutralizable matter from the caustic treated product, treating the saponifiable and neutralizable matter with acidic material, and separating the water-soluble saponifiable and neutralizable matter from the acidtreated saponifiable and neutralizable matter; the improvement. which comprises treating said water-soluble saponifiable and neutralizable matter with 'a basic alkali-metal compound to form an alkali-metal salt of said water-soluble saponifiable and neutralizable matter, reacting said alkali-metal salt with a halogen-substituted polymethylbenzene to form a reaction product, extracting said reaction product with a nonpolar hydrocarbon solvent, and topping the extract thus obtained, to obtain, as the residue, the polymethylbenzyl esters or" said water-soluble saponifiable and neutralizable matter.

2. In the process which includes oxidizing a hydrocarbon mixture containing upwards of about by volume of aliphatic and naphthenic hydrocarbons and boiling above about 300 F. to produce an oxidized product, treating the oxidized product witha caustic material to saponify and neutralize the saponifiable and neutralizable matter present in said oxidized product, separat ing the saponifiable and neutralizable matter from the caustic treated product, treating the saponifiable and neutralizable matter with acidic material, and separating the water-soluble saponifiable and neutralizable matter from the acidtreated saponifiable and neutralizable matter; the improvement which comprises treating said Water-soluble saponifiable and neutralizable matter with a basic alkali-metal compound to form an alkali-metal salt of said water-soluble saponifiable and neutralizable matter, reacting said alkali-metal salt with a chlorine-substituted polymethylbenzene toform a reaction product, extracting said reaction product with a non-polar hydrocarbon solvent, and topping the extract, thus obtained, to obtain, as the residue, the polymethylbenzyl esters of said water-soluble saponifiable andneutralizable matter.

3. In the process which includes oxidizing a hydrocarbon mixture containing upwards of about 80% by volume of aliphatic and naphthenic hydrocarbons and boiling above about 300 F. to produce an oxidized product, treating the oxidized product with a caustic material to saponify and neutralize the saponifiable and neutralizable matter present in said oxidized product, separating the saponifiable and neutralizable matter from the caustic treated product, treating the saponifiable and neutralizable matter with acidic material, and separating'the water-soluble saponifiable and neutralizable matter from the acidtreated saponifiable and neutralizable matter; the improvement which comprises treating said water-soluble saponifiable and neutralizable matter with an aqueous solution of an alkali-metal hydroxide to form an alkali-metal salt of said water-soluble saponifiable and neutralizable matter, reacting said alkali-metal salt with a chlofine-substituted polymethylbenzene to form a reaction product, extracting said reaction product with a non-polar hydrocarbon solvent, and topping the extract, thus obtained, to obtain, as the residue the polymethylbenzyl esters of said water-soluble saponifiable and neutralizable matter.

4. In the process which includes oxidizing a hydrocarbon mixture containing upwards of about 80% by volume of aliphatic and naphthenic hydrocarbonsand boiling above about 300 F. to produce an oxidized product, treating the oxidized product with'a caustic'material to saponify and neutralize the sapcnjifiahle and,.neu tralizab1e matter present in said, oxidizedproduct, separating the saponifiable and neutralizable matter from the caustic treated product, tr'eating the saponifiable and neutralizable matter with acidic material, and separating the water-soluble saponifiable and neutralizable matter from the acid-treated saponifiable and neutralizable matter; the improvement which comprises treating said water-soluble saponifiable and neutralizable matter with an aqueous solution of an alkali-metal hydroxide to form an alkali-metal salt of said water-soluble saponifiable and'neutralizable matter, reacting said alkali-metal salt with a chlorinated aromatic petroleum fraction to form a reaction product, extractingsaid reaction product with a non-polar hydrocarbon solvent, and topping the extract, thus'obta-ined; to-obta-i-n,- as the residue the polymethylbenzylesters of said water-soluble saponifiable and neutralizable matter.

5. In the process which includes oxidizing a hydrocarbon mixture containing upwardsof about 80% by volume of a-liphatic and naphthenic hydrocarbons and boiling aboveabout-300 Fwto produce an oxidized product; treating theoxidized product with a caustic material =tosaponify and neutralize the saponifiable and neutralizable matter present in said oxidized product, separating the saponifiable and neutralizable matter from the caustic treated product,- treating the saponifiable and neutralizable matter with acidic material, and separating the'water-soluble saponifiable and neutralizable matter from the acid-treated saponifiable and neutralizable mat ter; the improvement which comprises treating said water-soluble-saponifiable and neutralizable matter with an aqueous solution ofan alkalimetal hydroxide to form an alkali-metal salt oi said water-soluble saponifiable and neutralizable matter, reacting said alkali-metal salt with trimethylbenzylchloride to form a reaction product; extracting said reaction product with a non-polar hydrocarbon solvent, and topping the extract, thus obtained, to obtain, as the residue the trimethylbenzyl esters of said water-soluble saponifiable and neutralizable matter.

In t e p s vwhi h- I i iesfi ifnl zi ie a b dl'ocalbon miXtuYe nta nin .PW.&1T ,..Qi 91. 80 by volume of aliphatic andflnaphthenic, hydrocarbons and boilingaboveab9ut 300 F; to produce an oxidized product, treating the oxi= dized product with a caustic material to, saponiiy and neutralize the saponifiable and neutralizabie matter present in Said oxidized product, sepa: rating the saponifiable and neutralizabie matter from the caustic treated product, treating the sa: ponifiable and neutralizable matter with acidic material, and separating the water-soluble saponifiable and neutralizable matter from the acid-treated saponifiable, and neutralizable matter; the improvement which comprises treating said water-soluble saponifiable and neutralizabie matter with an aqueous solution of, an alkalie metal hydroxide to form an callgalirmetal saltoi said water-soluble saponifiableandneutralizable matter, reacting said alkali-metal salt with a halogen-substituted polymethylbenzene toform a reaction product, extracting said reaction product with a non-polar aliphatic hydrocarbon solvent, and topping the extract, thus obtained, to obtain, as the residue the polymethylbenzyl esters of said wateresoluble saponifiable and neutral zah e mat ter.

7. Inthe process whichincludesuoxidizing a hrdr carb a m xture, containi upwards 0? about 50% by volume of aliphatic and naphthenic hydrocarbons and bo ling above about 300 F, to produce an oxidized product, treating the oxidized product with a caustic material to saponiiy and neutralize rthe saponifiable and neutralizab1ematter, presentin said oxidized product, separating the saponifiable and neutralizable matter'from the caustic treated product, treating the saponiflable and neutralizable matter with acidic ma; terial, and'separating the water-soluble saponi: fiable and neu'tralizable matter from the, acid; treated saponifiable and neutralizable matter; the improvement which comprises treating said water-soluble saponifiable and neutralizable mat-. ter with an aqueous solution of an alkali-metal hydroxide to form an alkali-metal salt of said water-soluble saponifiable and neutralizable matter, reacting said alkali-metal salt with a halogen-substituted polymethylbenzene to form a reaction product, extracting said reaction product with a non-polar aromatic hydrocarbon solvent, and topping the extract, thus obtained, to obtain, as the residue the polymethylbenzyl esters of said water-soluble saponifiable and neutralizable matter.

8. In the process which includes oxidizing a hydrocarbon mixture containing upwards of about by volume of aliphatic and naphthenic hydrocarbons and boiling above about 300 F. to produce an oxidized product, treating the oxidized product with a caustic material to saponify and neutralize the saponifiable and neutralizable matter present in said oxidized product, separatin the saponifiable and neutralizable matter from the caustic treated product, treating the saponifiable and neutralizable matter with acidic material, and separating the water-soluble saponifiable and neutralizable matter from the acid-treated saponifiable and neutralizable matter; the improvement which comprises treating said water-soluble saponifiable and neutralizable matter with an aqueous solution of an alkali-metal hydroxide to form an alkali-metal salt-of said water-so1ub1e saponifiable and; neutralizable matter, reacting said alkaliwmetal salt with a halo en-substituted polymethylbenzene to form a reaction product, extracting said reaction product with benzene, and topping the extract, thus obtained, to obtain, as the residue the polymethylbenzyl esters of said water-soluble saponifiable and neutralizable matter.

9. In the process which includes oxidizing a hydrocarbon mixture containing upwards of about 80% by volume of aliphatic andnaphthenic hydrocarbons and boiling above about 300 F. to produce an oxidized product, treating the oxidized product with a caustic material to saponify and neutralize the saponifiable and neutralizable matter present in said oxidized product, separating the saponifiable and neutralizable matter from the caustic treated product, treating the saponifiable and neutralizabie matter with. acidic material, and separating the water-soluble saponifiable and neutraliz able matter from the acid-treated saponifiable and neutralizable matter; the improvement which comprises treating said water-soluble saponifiable and neutralizable matter with an aqueous solution of an alkali-metal hydroxide to form an alkali-metal of said water-soluble saponifiable and neutralizable matter, reacting said alkalimetal salt with a chlorinated aromatic petroleum fraction to, form a reaction product, extracting said reaction product with benzene, and topping the extract, thus obtained, to obtain, as the residue the polymethylbenzyl esters of said water-soluble saponifiable and neutralizable matter.

10. In the process which includes oxidizing a hydrocarbon mixture containing upwards of about 80% by volume of aliphatic and naphthenic hydrocarbons and boiling above about 300 F. to produce an oxidized product, treating the oxidized product with a caustic material to saponify and neutralize the saponifiable and neutralizable matter present in said oxidized product, separating the saponifiable and neutralizable matter from the caustic treated product, treating the saponifiable and neutralizable matter with acidic material, and separating the water-soluble saponifiable and neutralizable matter from the acid-treated 'saponifiable and neutralizable matter; the improvement which comprises treating said water-soluble saponifiable and neutralizable matter" with an aqueous REFERENCES CITED The following references are of record in the file of this patent:

Ellis, Chem. of Petroleum Derivatives, vol. II, pp. 962-964 (1937). 

1. IN THE PROCESS WHICH INCLUDES OXIDIZING A HYDROCARBON MIXTURE CONTAINING UPWARDS OF ABOUT 80% BY VOLUME OF ALIPHATIC AND NAPHTHENIC HYDROCARBONS AND BOILING ABOVE ABOUT 300* F. TO PRODUCE AN OXIDIZED PRODUCT, TREATING THE OXIDIZED PRODUCT WITH A CAUSTIC MATERIAL TO SAPONIFY AND NEUTRALIZE THE SAPONIFIABLE AND NEUTRALIZABLE MATTER PRESENT IN SAID OXIDIZED PRODUCT, SEPARATING THE SAPONIFIABLE AND NEUTRALIZABLE MATTER FROM THE CAUSTIC TREATED PRODUCT, TREATING THE SAPONIFIABLE AND NEUTRALIZABLE MATTER WITH ACIDIC MATERIAL, AND SEPARATING THE WATER-SOLUBLE SAPONIFIABLE AND NEUTRALIZABLE MATTER FROM THE ACIDTREATED SAPONIFIABLE AND NEUTRALIZABLE MATTER; THE IMPROVEMENT WHICH COMPRISES TREATING SAID WATER-SOLUBLE SAPONIFIABLE AND NEUTRALIZABLE MATTER WITH A BASIC ALKALI-METAL COMPOUND TO FORM AN ALKALI-METAL SALT OF SAID WATER-SOLUBLE SAPONIFIABLE AND NEUTRALIZABLE MATTER, REACTING SAID ALKALI-METAL SALT WITH A HALOGEN-SUBSTITUTED POLYMETHYLBENZENE TO FORM A REACTION PRODUCT, EXTRACTING SAID REACTION PRODUCT WITH A NONPOLAR HYDROCARBON SOLVENT, AND TOPPING THE EXTRACT THUS OBTAINED, TO OBTAIN, AS THE RESIDUE, THE POLYMETHYLBENZYL ESTERS OF SAID WATER-SOLUBLE SAPONIFIABLE AND NEUTRALIZABLE MATTER. 